I think I get the gist of that gem of a sentence, hopefully everyone has
gleaned just a little from your self-professed knowledge, they're probably
psychics.


"JAXAshby" wrote in message
...
certainly no expects you to understand, ac, one liners or ten thousand.

From: "AC"
Date: 8/23/2004 12:13 AM Eastern Daylight Time
Message-id:

Are you the "ng"? I hope not, since if you are, that would make you some
sort of one-sentence-replying dictator, expecting everyone else to
understand your prophetic one-liners.


"JAXAshby" wrote in message
...
ac, you lack totally and utterly ANY understanding of what is going
on --
airfoilwise -- on either or, same same, a sailboat sail.

ac, the ng askes that you NEVER post on this subject again. for the
obvious
reason.

From: "AC"
Date: 8/21/2004 5:50 PM Eastern Daylight Time
Message-id:

The answer to your question, is yes. Sails are made from dacron for
ease
of
handling & shortening, and cost. Many examples of rigid-wing vessels
exist,
I suggest doing a search on that. They often use fairings at the
leading
edge, or movable trailing edges to fine tune the foil.

An aircraft can fly inverted, because its angle-of-attack changes to
suit
the correspondingly lower efficiency of the foil in this position. As
others
have noted, acrobatic craft often employ nearly symmetrical foils for
this
reason. A normally profiled foil will fly inverted, but inefficiently,
and
at a much lower VMG due to the increased drag from the higher angle of
attack.

Try some "Bernoulli experiments for kids",and you will reach a better
understanding.

"Axel Boldt" wrote in message
om...
Hi,

I'm trying to understand how a boat can sail against the wind.
Explanations on the internet usually go like this: "The sail has an
airfoil shape, the air goes faster on one side than on the other,
creating lift by Bernouilli's principle." But I know that for flying
planes, the wing's airfoil shape is not essential (otherwise planes
couldn't fly on their back): it's the angle of attack that matters.
So
I'm wondering if the same is true for sailing: would it be possible
to
sail against the wind with a sail that's a rigid flat surface, not
an
airfoil-shaped piece of cloth?

Thanks,
Axel

little boy, you don't understand. *YOU* are not worth proofreading for grammar
or spelling.


From: "AC"
Date: 8/25/2004 1:06 AM Eastern Daylight Time
Message-id:

Oooohh, great - name calling. Now, we're really expressing ourselves well,
aren't we?

I can tell the limitation of your cred's by your grammar. I bet you can't
tell what mine are...

You can click on as many hyperlinks as you want, and be a wannabe pilot all
your life, but still not receive basic physics training, that's a two-way
experience.


"JAXAshby" wrote in message
...
just dipsquats who pretend to know things they utterly and knowingly
ignorant
of.

ac, you lack totally and utterly ANY understanding of what is going
on --
airfoilwise -- on either or, same same, a sailboat sail.

ac, the ng askes that you NEVER post on this subject again. for the
obvious
reason.



Jax,
Do you intend to annoy people, or is it just by accident?

You've completely lost me there... paaaaLOnk


"JAXAshby" wrote in message
...
little boy, you don't understand. *YOU* are not worth proofreading for
grammar
or spelling.


From: "AC"
Date: 8/25/2004 1:06 AM Eastern Daylight Time
Message-id:

Oooohh, great - name calling. Now, we're really expressing ourselves
well,
aren't we?

I can tell the limitation of your cred's by your grammar. I bet you can't
tell what mine are...

You can click on as many hyperlinks as you want, and be a wannabe pilot
all
your life, but still not receive basic physics training, that's a two-way
experience.


"JAXAshby" wrote in message
...
just dipsquats who pretend to know things they utterly and knowingly
ignorant
of.

ac, you lack totally and utterly ANY understanding of what is going
on --
airfoilwise -- on either or, same same, a sailboat sail.

ac, the ng askes that you NEVER post on this subject again. for the
obvious
reason.



Jax,
Do you intend to annoy people, or is it just by accident?

what a surprise. you are lost all too often.

From: "AC"
Date: 8/26/2004 10:58 PM Eastern Daylight Time
Message-id:

You've completely lost me there... paaaaLOnk


"JAXAshby" wrote in message
...
little boy, you don't understand. *YOU* are not worth proofreading for
grammar
or spelling.


From: "AC"
Date: 8/25/2004 1:06 AM Eastern Daylight Time
Message-id:

Oooohh, great - name calling. Now, we're really expressing ourselves
well,
aren't we?

I can tell the limitation of your cred's by your grammar. I bet you can't
tell what mine are...

You can click on as many hyperlinks as you want, and be a wannabe pilot
all
your life, but still not receive basic physics training, that's a two-way
experience.


"JAXAshby" wrote in message
...
just dipsquats who pretend to know things they utterly and knowingly
ignorant
of.

ac, you lack totally and utterly ANY understanding of what is going
on --
airfoilwise -- on either or, same same, a sailboat sail.

ac, the ng askes that you NEVER post on this subject again. for the
obvious
reason.



Jax,
Do you intend to annoy people, or is it just by accident?

"AC" wrote in message ...
The answer to your question, is yes. Sails are made from dacron for ease of
handling & shortening, and cost. Many examples of rigid-wing vessels exist,
I suggest doing a search on that. They often use fairings at the leading
edge, or movable trailing edges to fine tune the foil.

An aircraft can fly inverted, because its angle-of-attack changes to suit
the correspondingly lower efficiency of the foil in this position. As others
have noted, acrobatic craft often employ nearly symmetrical foils for this
reason. A normally profiled foil will fly inverted, but inefficiently, and
at a much lower VMG due to the increased drag from the higher angle of
attack.

The profile of the wing only handles the Drag, not Lift.

Angle of attack handles Lift (see the Cl/Alfa diagram)!

Try some "Bernoulli experiments for kids",and you will reach a better
understanding.


Bernoulli experiments are all due to other physical effects like
boundary layer (asymmetric) separation, entrainment of air, Coanda
effect etc.

The thought that " a change in air velocity will change the pressure"
is not real, only mathematic relations.


Jan-Olov Newborg

The profile of the wing only handles the Drag, not Lift.

ah, no.

Try some "Bernoulli experiments for kids",and you will reach a better
understanding.

no, you won't. wings/sails do not have lift because of "Bernoulli" inspite of
the fact you can read such in thousands of kiddie books.

Hi Axel,

there is a nice flash movie explaining this on www.bmw-yachtsport.com,
look for "Physik des Segelns". It's in german but I think that's no
problem for you :-)

Have a nice weekend,

Joachim

Axel Boldt schrieb:

Hi,

I'm trying to understand how a boat can sail against the wind.
Explanations on the internet usually go like this: "The sail has an
airfoil shape, the air goes faster on one side than on the other,
creating lift by Bernouilli's principle." But I know that for flying
planes, the wing's airfoil shape is not essential (otherwise planes
couldn't fly on their back): it's the angle of attack that matters. So
I'm wondering if the same is true for sailing: would it be possible to
sail against the wind with a sail that's a rigid flat surface, not an
airfoil-shaped piece of cloth?

Thanks,
Axel

Jax,

How much have you studied the response of sails?

By studied, I mean with real data from instruments calibrated to
accepted standards and in standardized conditons.

If not Bernoulli, Then perhaps you will explain to the readers how the
Kutta-Zhukovsky Theorem can explain everything without assistance of the
equations set out by Daniel Beroulli. Or, did you have something else
in mind?

Matt Colie (CV by request only)

JAXAshby wrote:
Try some "Bernoulli experiments for kids",and you will reach a better
understanding.


no, you won't. wings/sails do not have lift because of "Bernoulli" inspite of
the fact you can read such in thousands of kiddie books.

(JAXAshby) wrote in message ...
Try some "Bernoulli experiments for kids",and you will reach a better
understanding.

no, you won't. wings/sails do not have lift because of "Bernoulli" inspite of
the fact you can read such in thousands of kiddie books.

Yes you will. Been there done that. Its fun and will definitely teach
you allot of how aerodynamics works in the real world. These simple
"Bernoulli experiments for kids" can show you exactly how a wing or
most any solid object can generate lift as a result of the Bernoulli
effect. You could write a book on what these experiments will teach
you.

In a feeble attempt to prove the misconception that an airplane wing
(while in normal flight) produces lift as a result of Bernoulli
effect, these kiddy and adult books give perfect examples of Bernoulli
effect lift. My favorite is the levitating ball. The large problem
with this is that a wing in flight is not partially influenced by a
stream of air that has reduces internal pressure as a result of its
increased velocity. A wing in flight is totally submerged in the
relative airflow that is influencing it and many times this relative
airflow has no velocity at all because the aircraft is flying in still
air.

So to generate Bernoulli effect lift from a wing simply direct a jet
of air over the top of it. If you want a wing in normal flight to
produce Bernoulli effect lift your are pretty much crap out of luck as
you apparently already know.